mixing LFP batteries with different rating BMS

[1holaguy]

I have a small LiFePO4 battery bank made up of 100 Ah 12V batteries with 1C discharge rate and 100 Amp BMS. I was offered some additional batteries that are the same except some have 100 Amp BMS and others have 200 Amp BMS. Does the difference in the rating effect how the batteries charge and discharge in a real world application? I realize that the BMS rated at 200 amp can maintain a higher continuous discharge but I am assuming that the discharge rate will be determined by the lowest denominator. IN this case then the batteries would all discharge at a max rate of 100 amps. If it makes a difference, these are all connected in series to 3Kw 12vdc to 120 vac inverter/converter with a max charge rate of 100 Amps.

 

[Supervstech]

I have a small LiFePO4 battery bank made up of 100 Ah 12V batteries with 1C discharge rate and 100 Amp BMS. I was offered some additional batteries that are the same except some have 100 Amp BMS and others have 200 Amp BMS. Does the difference in the rating effect how the batteries charge and discharge in a real world application? I realize that the BMS rated at 200 amp can maintain a higher continuous discharge but I am assuming that the discharge rate will be determined by the lowest denominator. IN this case then the batteries would all discharge at a max rate of 100 amps. If it makes a difference, these are all connected in series to 3Kw 12vdc to 120 vac inverter/converter with a max charge rate of 100 Amps.

No possible way to connect 12V batteries in series and maintain 12V... you meant parallel.
The 200A in parallel would simply tie into the bank. No issues. And in parallel, the 200A battery will be able to output 200A into the bank, while the rest all put out 100A each... as long as there are at least 2 other 100A batteries tied in, and ALL the cables are able to handle the current... or you have a bussbar able to handle the current.

 

[MattiFin]

The 200A in parallel would simply tie into the bank. No issues. And in parallel, the 200A battery will be able to output 200A into the bank, while the rest all put out 100A each... as long as there are at least 2 other 100A batteries tied in, and ALL the cables are able to handle the current... or you have a bussbar able to handle the current.

Connecting batteries in parallel is bit more complicated than that, especially when there is multiple BMS's involved. Ideally you'd use identical batteries with same cell type, age and cycle history so that they have similar internal impedance and pulse response. Not having that luxury results in less than perfect current sharing.
Worst-case scenario would be fresh low impedance cells and 100A BMS on one battery and not-so-low impedance cells and 200A BMS on another battery. OP stated that the batteries are same except BMS design so its fairly safe to assume that they share current at least somewhat satisfactorily. I'd guess that 200+100A combo would be safe up to 250A and 200+100+100A combo up to 300A.

 

[1holaguy]

No possible way to connect 12V batteries in series and maintain 12V... you meant parallel.
The 200A in parallel would simply tie into the bank. No issues. And in parallel, the 200A battery will be able to output 200A into the bank, while the rest all put out 100A each... as long as there are at least 2 other 100A batteries tied in, and ALL the cables are able to handle the current... or you have a bussbar able to handle the current.

Correct. That is what I get for writing on the forum at 1:40 in the morning. I meant PARALLEL to maintain 12vdc